In the sheet metal working industries it is often necessary to produce notches in sheet metal with right angle cuts and other sharp inside corners. Many of these applications require other irregular cut configurations that do not extend the entire width of the sheet. Steel, Stainless steel, aluminum, and copper are commonly available in sheets. Other metals and non-metals are used in relatively thin gauges that can be cut with conventional metal scissors referred to as tin snips or aviation snips. Some of the uses are for heating, ventilation, and air conditioning ductworks; electronic chassis; aircraft construction and repair; automobile repair; and metal roofs, roof trim, and gutters.
Presently notches are produced by making two parallel cuts with conventional tin snips or aviation snips as shown in FIGS. 8 and 9. After the parallel cuts are completed the blind end is still intact. This blind end is roughly cut by various techniques such as making diagonal cuts 57, 58, and 59 curved toward the blind end line. Protrusion 60 remains as shown in FIG. 9 The protrusion 60 may be filed to remove the rough edges as shown in FIGS. 8 and 9, or with a hammer and chisel cutting against an anvil. Currently there is no sheet metal shear tool on the market that can make these end cuts. This inventor has collected hundreds of hand-operated pliers and cutters for 30 years and has reviewed, patents, old tool catalogs, tool books, and has visited many museums and tool collections for 30 years. I have not seen evidence of a sheet metal end shear tool with the capabilities of the Hand operated end cutting sheet metal shear of this patent.
There are three categories of tools that produce cuts at an angle to straight-line snip cuts. They are nibblers, nippers, and notchers. Each of these categories is described below with example patents.
Nibblers are cutters that are used mainly in the electronic fabrication and repair business. They have a blade that is generally a small rectangular bar with cutting edges on three sides and sufficiently small to pass through a small hole. They are used to produce rectangular openings from round holes. They are light duty tools that creates or enlarges opening by cutting and removing small chips approximately {fraction (1/16)} inch long by xc2xc inch wide chips. These chips do remove a portion of material. Because of these tools small size and their simple lever ratios they are not capable of producing the high forces required for making thick or wide cuts. The blade rod moves linearly in a slot with clearance to allow sliding. This clearance reduces the accuracy of the cut and allows slivers of metal, which can bind the cutting bar, or produce rough cuts and burrs. These nibblers leave debris and require considerable time in producing large notches, and their construction and their linkage precludes cutting heavy gage material or from making larger cuts. They differ from the end shear of this patent in that they cannot make continuous single cuts and they cannot cut to either side because of the non cutting portion of the blade bar. Examples of nibbling tools:
U.S. Pat. No. 2,542,103 Adel discloses the tool may be held in one hand to make a margin in a piece of sheet material by cutting away chips from the periphery of the opening.
U.S. Pat. No. 4,173,070, Vistain, discloses the cutter element has a shank portion which is arranged for reciprocation through an aperture formed in the flange portion of the cutter support. The shank portion is relieved to provide an upper cutting edge and a lower angular edge parallel to it which acts as a guide for discharging chips.
U.S. Pat. No. 2,598,287, Murphy discloses a means for cutting out rectangular and other areas in sheet metal when the edge is not accessible or when the area to be cut does not start from the edge of the sheet. It is capable of cutting out a given area in a metal sheet piece by piece until the entire area is open.
Nippers are cutting tools with cutting edges parallel to the axis of rotation of the blades; as opposed to parallel to the handles in diagonal cutters. The blades are aligned so that they abut, producing a pinch cut rather than a shear cut. They are used to cut soft wires by pinching the material. Nippers have been used for hundreds of years for removing horseshoes and trimming horse hooves, in preparation for shoeing. They cannot be used on sheet metals because the ductility allows the material to be pinched and thinned but not fractured. These devices cannot generate high forces because of the simple lever ratios. They can cut weak or brittle materials and narrow items such as screws, nails, wire, and protrusions. The nippers may also be used for trimming tree branches, other brush, and trimming the flash and excess plastic from molded plastic parts. Examples of nipping tools are:
U.S. Pat. No. 5,987,752 Swanstrum, Jr discloses a nipper tool which is used to shape and trim a horses hoof to the shape necessary to attach a shoe. The two nipper blades are opposed blades and they abut to pinch the work object. The xe2x80x9cVxe2x80x9d shaped portions act as wedges to compress the material to allow the blades to abut each other. The nippers may also be used for trimming tree branches, other brush, and trimming the flash and excess plastic from molded plastic parts.
U.S. Pat. No. 2,202,340, Faist, discloses a device is adapted for use in cutting off the ends of screws, rivets, dowel pins, or mounting eye glasses.
U.S. Pat. No. 532,509, Whiting discloses cutting nippers with adjustable blades and a stop device to limit the closing movement of the blades in accordance with their adjustment and to prevent the blades from closing injuriously upon each other.
U.S. Pat. No. 5,107,559 Oxe2x80x3Reilley discloses a device used as a pry and nail puller. The jaws are inserted beneath the shoe and the handles are squeezed to pry the shoe loose.
U.S. Pat. No. 562,746 discloses a tool that is intended for use in constructing and tearing down fences, and for pulling nails and staples.
Notchers are a class of sheet metal tools which cut on three sides like nibblers and remove a width of material, but they are generally used to cut a notch in an edge of sheet metal to form a specific shaped cutout. They are limited in the depth of notch cut because of the tool body is wider than the width of cut. Examples of notchers are:
U.S. Pat. No. 5,483,746 discloses a slot-forming tool that has dual cutting edges and an elongated nose portion having a mechanically advantaged dual edged cutting blade which is pivotly mounted over a dual slotted anvil.
U.S. Pat. No. 2,224,226 Jensen Discloses a tool for enabling xe2x80x9cVxe2x80x9d shaped notches to be cut along the edge of a piece of sheet metal. It has two pivoted cross-levers.
U.S. Pat. No. 4,753,011 Long discloses a cutter with two semi-elliptical sides with dual cutting edges.
U.S. Pat. No. 5,033,194 Long discloses an upper cutter that slides in a raceway and is forced downward through a work piece into the lower cutter shearing out a segment of the workpiece.
U.S. Pat. No. 1,812,350 Lingwood discloses a through slotted jaw carried by one arm forming an anvil, a cutting jaw which at each cutting operation removes a portion of the sheet metal.
The device is shaped and operates similar to conventional locking pliers. The device has a shear anvil and a shear blade at the tool end opposite the handle. The cutting action is perpendicular to the tool handle, rather than parallel to the handle such as snips or scissors type cutters have. The present invention includes a device and a method of cutting, notching or slotting pieces of sheet metal stock. It can be used where removal of a slot-shaped cutout is desired. The hand-operated, end-cutting tool may be conveniently carried to the job site and used to produce end cuts that cannot be made with metal snips. This tool has been reduced to practice and has reliably produced hundreds of end shear cuts.